The present invention relates to a new subtype of the P2-purnergic receptors, which is abundantly expressed in kidney and in many cell lines of megakaryocytic or erythroleukemic origin. Referred to herein as the P2U2 receptor, this receptor is activated by ATP, ADP, UTP and UDP. The P2U2 receptor can be used as a tool to screen for agonists and antagonists that can either stimulate or block receptor activation. Such compounds have therapeutic utility in treating (1) diseases that are caused by aberrant activation of this receptor, for example over stimulation or under stimulation of the receptor and (2) diseases whose symptoms can be ameliorated by stimulating or inhibiting the activity of the P2U2 receptor.
The present invention also relates to the isolated entire human gene encoding the P2U2 receptor, methods for the recombinant production of purified P2U2 receptor proteins and the proteins made by these methods, antibodies against the whole P2U2 receptor or regions thereof, vectors, nucleotide probes, and host cells transformed by genes encoding polypeptides having the P2U2 receptor activity, along with diagnostic and therapeutic uses for these various reagents.
Purinergic receptors are cell surface receptors that interact with extracellular adenine or uridine nucleotides and nucleosides. These receptors are present throughout the central nervous system and peripheral tissues and play a role in numerous physiological responses.
The purinergic receptors are broadly divided into two major receptor types, P1 and P2, which are defined by their level of interaction with the adenine nucleotides and nucleosides. Where P1 receptors are activated by adenosine and exhibit a potency order of adenosine greater than AMP greater than ADP greater than ATP, P2 receptors are activated by ATP, UTP, ADP or UDP and exhibit a potency order of ATPxe2x89xa7ADP greater than AMP greater than adenosine. As more has become known about the purinergic receptors and the wide range of physiological responses in which they play a role, the P1- and P2-type classifications were no longer sufficient to accurately portray this complex family of receptors. Therefore, receptor subtype categories have been developed. For example, the P2-type purinergic receptors are now classified as P2y-, P2U- , P2T-, P2X- and P2Z-subtypes. A review of the P2-type purinergic receptors can be found in Harden, et al., Ann. Rev. Pharmacol. Toxicol. 35:541-579 (1995).
Classification of the P2-type purinergic receptors has been difficult because there are no published selective P2-receptor antagonists and there are few ATP or ADP receptor-subtype specific agonists. In addition, it has been difficult to compare the relative order of potency of P2-purinergic receptor agonists. Hence, this subtype has presented numerous challenges in the identification and characterization of its members.
One aspect of the invention is an isolated and purified polypeptide comprising the amino acid sequence of FIG. 1 (SEQ ID NO:2).
Another aspect of the invention is an isolated and purified nucleic acid sequence encoding for the P2U2 receptor.
Yet another aspect of the invention is an isolated and purified nucleic acid sequence comprising the nucleotide sequence of FIG. 1 (SEQ ID NO:1).